EP-4531007-B1 - ULTRASONIC FINGERPRINT APPARATUS AND ELECTRONIC DEVICE

EP4531007B1EP 4531007 B1EP4531007 B1EP 4531007B1EP-4531007-B1

Inventors

DU, Canhong
JI, Dengxin
XU, YUWANG
WANG, Chengzuo
WANG, HONGCHAO

Dates

Publication Date: 20260506
Application Date: 20220913

Claims (15)

An ultrasonic fingerprint apparatus, being arranged under a display screen of an electronic device to implement under-display ultrasonic fingerprint identification, wherein the ultrasonic fingerprint apparatus comprises an ultrasonic fingerprint chip and a piezoelectric transducer arranged above the ultrasonic fingerprint chip; the piezoelectric transducer comprises a piezoelectric layer, an upper electrode located above the piezoelectric layer, and a lower electrode located below the piezoelectric layer; wherein the ultrasonic fingerprint chip comprises a substrate and a plurality of metal layers arranged in a first region of the substrate, the lower electrode is located above a second region of the substrate, a top metal layer among the plurality of metal layers comprises N drive traces, N=1 or N is a positive integer greater than 1, a passivation layer is provided above the top metal layer, and provided with a first window corresponding to the N drive traces, and the upper electrode extends from an upper surface of the piezoelectric layer into the first window for connection to respective first connection regions of the N drive traces located in the first window.
The ultrasonic fingerprint apparatus according to claim 1, wherein the first window comprises N sub-windows corresponding to the N drive traces, and a respective first connection region of each of the drive traces is located in a sub-window corresponding to the drive trace.
The ultrasonic fingerprint apparatus according to claim 1 or 2, wherein the substrate is a silicon substrate, and the passivation layer is further provided with N second windows corresponding to the N drive traces, wherein a second connection region of each of the drive traces located in its corresponding second window is connected to a circuit board below the ultrasonic fingerprint chip through a corresponding lead wire.
The ultrasonic fingerprint apparatus according to any one of claims 1-3, wherein the piezoelectric layer extends onto the plurality of metal layers, the N drive traces extend into the piezoelectric layer, and the first connection regions of the N drive traces are adjacent to the piezoelectric layer.
The ultrasonic fingerprint apparatus according to claim 4, wherein a size of the first window is larger than a size of the first connection regions of the N drive traces, the upper electrode extends from the upper surface of the piezoelectric layer into a first part of the first window to cover the first connection regions of the N drive traces, and a second part of the first window is located under the piezoelectric layer.
The ultrasonic fingerprint apparatus according to claim 5, wherein a size of the first part in a direction of the N drive traces is larger than or equal to 150 um; and/or a size of the second part in the direction of the N drive traces is larger than or equal to 20 um.
The ultrasonic fingerprint apparatus according to any one of claims 1-6, wherein a region corresponding to the N drive traces in a first metal layer among the plurality of metal layers is punched, wherein the first metal layer is an adjacent metal layer located below the top metal layer.
The ultrasonic fingerprint apparatus according to claim 7, wherein the region corresponding to the N drive traces in the first metal layer and a surrounding region extending 12 um or more in all directions from the region are punched.
The ultrasonic fingerprint apparatus according to any one of claims 1-8, wherein a region corresponding to the N drive traces in a second metal layer among the plurality of metal layers is grounded, wherein the second metal layer is an adjacent metal layer located below the first metal layer.
The ultrasonic fingerprint apparatus according to claim 9, wherein the region corresponding to the N drive traces in the second metal layer and a surrounding region extending 12 um or more in all directions from the region are grounded.
The ultrasonic fingerprint apparatus according to any one of claims 1-10, wherein the top metal layer is provided with a bonding pad for grounding, and the bonding pad is arranged beside the second connection regions of the N drive traces.
The ultrasonic fingerprint apparatus according to any one of claims 1-11, wherein a distance between the lower electrode and the passivation layer around the lower electrode is larger than or equal to 100 um; and/or the other traces adjacent to the lower electrode in the top metal layer are grounded; and/or a distance between an edge of the upper electrode and an edge of the piezoelectric layer is larger than or equal to 50 um.
The ultrasonic fingerprint apparatus according to any one of claims 1-12, wherein N=1, and an area of a part of the first window close to the piezoelectric layer is larger than an area of a part of the first window away from the piezoelectric layer; and/or a shape of the first window is a trapezoid, and a lower base of the trapezoid is closer to the piezoelectric layer than an upper base of the trapezoid.
The ultrasonic fingerprint apparatus according to claim 13, wherein a shape of the first window is an L-shape, the L-shape comprises a first part parallel to a direction of the drive traces and a second part perpendicular to the direction of the drive traces, and the second part is closer to the piezoelectric layer than the first part.
An electronic device, comprising: a display screen; and the ultrasonic fingerprint apparatus according to any one of claims 1-14, wherein the ultrasonic fingerprint apparatus is arranged under the display screen to implement under-display ultrasonic fingerprint identification.

Description

TECHNICAL FIELD Embodiments of the present disclosure relate to the field of fingerprint identification, and more specifically relate to an ultrasonic fingerprint apparatus and an electronic device. BACKGROUND With the social progress, a mobile phone has become one of essential electronic devices in modern life. At present, all mobile phones on the market have one or more identity authentication methods, including a digital password, a gesture pattern, face identification, fingerprint identification, and the like. Characterized by convenient application, fast identification speed, stability, reliability, and the like, fingerprint identification has become a standard configuration for most mobile phones. Different technical routes have developed for fingerprint identification, including capacitive fingerprint identification, optical fingerprint identification, ultrasonic fingerprint identification, and the like. Due to strong penetrability of ultrasound, ultrasonic fingerprint identification not only can identify surface appearance of a fingerprint, but also can identify a signal from a dermal layer of a finger. Therefore, ultrasonic fingerprint identification has gradually become a new method for fingerprint identification. The ultrasonic fingerprint apparatus generally includes a piezoelectric transducer and an ultrasonic fingerprint chip. How to achieve integration between the piezoelectric transducer and the ultrasonic fingerprint chip has become a to-be-solved problem. SUMMARY Embodiments of the present disclosure provide an ultrasonic fingerprint apparatus and an electronic device, which can achieve integration between a piezoelectric transducer and an ultrasonic fingerprint chip. In a first aspect, an ultrasonic fingerprint apparatus is provided, wherein the ultrasonic fingerprint apparatus is arranged under a display screen of an electronic device to implement under-display ultrasonic fingerprint identification, and includes an ultrasonic fingerprint chip and a piezoelectric transducer arranged above the ultrasonic fingerprint chip; the piezoelectric transducer includes a piezoelectric layer, an upper electrode located above the piezoelectric layer, and a lower electrode located below the piezoelectric layer; andthe ultrasonic fingerprint chip includes a substrate and a plurality of metal layers arranged in a first region of the substrate, the lower electrode is located above a second region of the substrate, a top metal layer among the plurality of metal layers includes N drive traces, N=1 or N is a positive integer greater than 1, a passivation layer is provided above the top metal layer, and provided with a first window corresponding to the N drive traces, and the upper electrode extends from an upper surface of the piezoelectric layer into the first window for connection to respective first connection regions of the N drive traces located in the first window. In an embodiment of the present disclosure, the top metal layer of the ultrasonic fingerprint chip includes drive traces for connection to the upper electrode, and the passivation layer above the top metal layer is provided with the first window corresponding to the drive traces. The upper electrode extends from the upper surface and an edge of the piezoelectric layer into the first window, and covers the first connection regions of the drive traces located in the first window, thereby achieving an electrical connection between the upper electrode and the drive traces, and achieving integration between the piezoelectric transducer and the ultrasonic fingerprint chip. Through the drive traces, a driving signal can be transmitted from a circuit board below the ultrasonic fingerprint chip to the piezoelectric transducer to excite the piezoelectric transducer to generate an ultrasonic signal for fingerprint identification. In addition, a signal of the upper electrode may be further led out to the circuit board through the drive traces. In an implementation, the first window includes N sub-windows corresponding to the N drive traces, and a respective first connection regions of each of the drive traces is located in a sub-window corresponding to the drive trace. In an implementation, the substrate is a silicon substrate, and the passivation layer is further provided with N second windows corresponding to the N drive traces, wherein a second connection region of each of the drive traces located in its corresponding second window is connected to the circuit board below the ultrasonic fingerprint chip through a corresponding lead wire. Due to the use of an ultrasonic fingerprint chip with a silicon substrate, a bonding process can be implemented on the ultrasonic fingerprint chip to connect the drive traces to the circuit board through the lead wire. In an implementation, the piezoelectric layer extends onto the plurality of metal layers, the N drive traces extend into the piezoelectric layer, and the first connection regions of the N drive traces a